It was resolved when they "[started] Utilities -> Disks, reformatted the drive, unplugged it, started the Tails installer, then plugged it back in".

This is a regression introduced in Tails Installer 4.4.19 and Tails 3.2~rc1. It certainly sounds like an inconsistency on how the installer is initialized vs how it reacts to changes (of plugging/unplugging drives).